The invention described herein may be manufactured and used by or for the Government of the United States of America for Governmental purposes without the payment of any royalties thereon or therefore.
Not applicable.
(1). Field of the Invention
The present invention relates generally to systems and methods for calibrating shipboard radio equipment and, more particularly, to a computerized outboard test facility to automate ship radio system test planning and operation.
(2). Description of the Prior Art
In order to test and calibrate a ship""s radio direction finding antennas and/or other testing, an outboard test facility is maintained having a plurality of antennas to generate, in most cases, a large number of different frequencies required by the ship. The tests are quite time consuming and may require up to two days of testing while the ship circles. It would be desirable to make the testing as efficient as possible because the ship normally has numerous duties and time is critical. The outboard test facility has to coordinate the testing schedules of numerous ships, the agents such as in-service engineering agents who monitor accurate completion of tests, and the facility""s own testing schedule. Extensive system checks and grooms are typically required. Pre-test briefings are required to set up all the testing requirements. Thus, it is highly desirable that testing proceeds as quickly as possible and without equipment failure.
The ship is required to perform a circular maneuver around a buoy or geodetic point of reference. The maneuver is required to be as circular as possible with the same angular velocity (constant turn rate). The number of measurements per quadrant, number of frequencies, and other factors will determine rudder angle and turning speed.
In the past, for each frequency, a test facility operator would need to set the bandwidth of the antennas to be used, make the physical connections between the signal source, amplifier and antennas and gradually increase the amplifier gain until the signal power output is maximized. At least two facility operators were required, one to control the signal generator/amplifier and one to read the spectrum analyzer to determine the optimum setting. Once set, the ship would verify it was receiving the signal and would commence its calibration for that frequency. Once calibrated, the process would be repeated for each frequency to be calibrated. The signal generator/amplifier settings for each frequency could be saved in hand written logs. However, due to the large number of frequency calibrations, which may typically be on the order of two hundred and fifty, the potential for log-in errors was high. Initial setting errors could lead to equipment failure if the system were brought on line at too high a power level. Therefore operators in the past have preferred to power up gradually, taking more time rather than relying on written logs, to avoid the risk of the possibility of equipment damage that would require the more extensive time for repairs and possibly create significant time requirement problems.
Various inventors have attempted to solve related problems as evidenced by the following patents, without providing the solutions taught hereinafter.
U.S. Pat. No. 4,884,078 issued Nov. 28, 1989, to Fishkin et al, discloses an improved antenna test and measurement system including a transmit antenna; means for providing a test signal to said transmit antenna and initiating the transmission thereof; a receive antenna adapted to receive the test signal as transmitted by said transmit antenna; an amplitude detector for detecting the amplitude of the received test signal; and an open loop phase detector for measuring the phase of the received test signal relative to a reference signal
U.S. Pat. No. 5,371,508, issued Dec. 6, 1994, to Teich et al., discloses a portable antenna test apparatus to provide a test set positioned a determined distance from a number of antennas of an aircraft. A transmitting module of the test set contains low frequency, mid frequency, and high frequency antennas connected to a radio receiver and power amplifier in and of the test set for receiving control commands and for transmitting a number of simultaneous test signals to the number of antennas in the aircraft. A signal generator produces low frequency, mid frequency and high frequency signals. A hand-held computer is connected to a communications radio in and of the aircraft via a radio interface adapter of the hand-held computer and a control computer is connected to the signal generator. The hand-held computer transmits commands via the aircraft radio, which commands are received by the receiver in the transmitting module. This receiver conveys the commands to the control computer which then programs the signal generator. By this means, an operator in the aircraft cockpit remotely controls the signal generator.
U.S. Pat. No. 5,396,255, issued Mar. 7, 1995, to Durkota et al., discloses an antenna test and measurement system that performs measurements of the transmitted or received signal strength of a vehicle mounted transmit or receive antenna with respect to all aspects of the system with respect to the vehicle mounted antenna, and vehicle state parameters, i.e., position and attitude, are simultaneously recorded. The antenna measurements are correlated with the state parameter measurements such that variations in the measured signal strength caused by changes in vehicle state are apparent. A graphical display of antenna signal strength and vehicle state parameters are presented for the entire 360 degree azimuth of an antenna test so that variations in the signal strength caused by changes in vehicle state parameters may be identified. The graphical display of antenna signal strength may be modified based on variations in vehicle state parameters such that the graphical display indicates the antenna signal strength had the variations in vehicle state not occurred. Antenna signal strength data and vehicle state information is telemetered from the vehicle carrying the antenna to the antenna test and measurement system. A graphical display of antenna signal strength versus antenna altitude is provided for determining the optimum altitude for antenna pattern measurements, and calculation of antenna isotropic is provided for verification of antenna performance.
U.S. Pat. No. 6,313,799, issued Nov. 6, 2001, to Thimm et al., discloses a diagnostic device having a diversity processor for individually testing the electrical condition of the connections of individual antennas of a multi-antenna system in a motor vehicle. This device can be coupled to the interfaces of an antenna amplifier containing a diversity system, and such a test can be carried out without any intervention in the circuitry of the receiving installation. The diagnostic device contains a test unit and a control unit. The test unit is designed for generating a test signal that is received by an antenna of the multi-antenna system by a transmitting antenna. The diversity system is acted upon by a control unit having a control signal consisting of an IF-signal and a dc voltage signal. The control signal generated by the control unit by an interference simulator integrated in the control unit is disturbed only when the diversity system is prompted to switch to the next antenna. The received power measured by the test unit on the output of the antenna amplifier can be antenna-specifically detected, stored and evaluated.
The above patents do not disclose a system and method for operable for controlling a plurality of test antennas with respect to planning a test program, repeating power up routines, and associated data analysis.
Accordingly, it is an objective of the present invention to provide an improved system and method for testing shipboard direction finding antenna systems.
Another objective is to provide a system and method as aforesaid which may be utilized to more efficiently control power settings of offboard antenna systems.
A further objective is to provide a system and method as aforesaid whereby computer controls may be utilized to safely power up a selectable associated patch interconnection of signal transmitting equipment and/or repeat power settings.
These and other objectives, features, and advantages of the present invention will become apparent from the drawings, the descriptions given herein, and the appended claims. However, it will be understood that the above listed objectives and advantages of the invention are intended only as an aid in understanding aspects of the invention, and are not intended to limit the invention in any way, and do not form a comprehensive list of objectives, features, and advantages.
Accordingly, the present invention provides a method for testing a ship direction finding antenna system for a client ship by utilizing an outboard facility while the client ship maneuvers around the circular course disposed in a predetermined position relative to the outboard facility. The method comprises one or more steps such as, for instance, entering into a memory of the outboard facility a list of radio frequency signals which the client ship desires in order for the client ship to test the ship direction finding antenna system and determining a test plan for transmitting a plurality of test signals comprising the list of radio frequency signals from the outboard facility with respect to the client ship and the circular course. Other steps may comprise making at least one patch interconnection between a selected of a plurality of signal generators of the outboard facility, a selected of a plurality of radio frequency amplifiers of the outboard facility, and a selected of the plurality of antennas at the outboard facility, wherein the at least one patch interconnection is operable for producing the list of radio frequency signals. Additional steps may comprise providing a computer screen with visual indicators to indicate a power setting for power control of the at least one patch interconnection, utilizing the visual indicators to increase a signal power produced by the at least one patch interconnection while monitoring a spectrum analyzer to produce an optimum signal power for each of the plurality of frequencies, and/or storing the optimum signal power for each of the plurality of frequencies with respect to the at least one patch interconnection. The method may further comprise contacting the client ship and broadcasting the list of frequencies utilizing the stored optimum power signals.
In a preferred embodiment, the computer screen displays details of the at least one patch interconnection and/or the computer screen displays a slide bar for indicating a level of the signal power.
The method may further comprise entering into the memory of the outboard facility a selected bandwidth for the list of radio frequencies and/or entering into the memory of the outboard facility a list of the plurality of antennas, the plurality of radio frequency amplifiers, and the plurality of signal generators. Preferably the invention further comprises providing that the test plan is optimized to reduce the amount of circling required by the client ship. In a presently preferred embodiment, the method comprises matching frequencies available from the plurality of signal generators to the list of frequencies and/or automatically generating the test plan. The method may further comprise selectively editing the automatically generated test plan.
Thus, the invention provides for an outboard facility for use with a client ship when calibrating a ship direction finding antenna system as the client ship maneuvers around a circular course. The outboard facility comprises a plurality of signal generators operable for producing generated signals at a plurality of frequencies and a plurality of radio frequency amplifiers with variable gains for amplifying the generated signals wherein the plurality of radio frequency amplifiers may be selectively interconnectable with each of the plurality of signal generators. Additional elements comprise a plurality of antennas wherein the plurality of antennas may be selectively interconnectable with each of the plurality of radio frequency amplifiers. A spectrum analyzer is operable for monitoring the plurality of antennas. A computer control is operable for storing the list of frequencies to be broadcast. The computer control may also be operable for storing a selected patch interconnection of one or more of the plurality of signal generators to one or more of plurality of radio frequency amplifiers and to one or more of the plurality of antennas. A computer screen is preferably provided with a visual indicator for a power level of the selected patch interconnection. The visual indicator may be selectively controllable by an operator for producing an optimum signal power as determined by the spectrum analyzer for the list of frequencies. The computer control is operable for storing the optimum signal power for the list of frequencies.
The computer control is operable for storing the test plan to broadcast the list of frequencies while the client ship maneuvers around a circular course. The computer control is preferably operable for storing data related to capabilities of the plurality of signal generators, the plurality of radio frequency amplifiers, and the plurality of antennas. In one embodiment, the computer control is operable for producing the test plan by matching the list of frequencies with the capabilities of the plurality of signal generators, the plurality of radio frequency amplifiers, and the plurality of antennas. The computer control is further operable for storing a test plan for one or more succeeding patch interconnections. Each succeeding patch interconnection is operable to broadcast at least one different frequency of the list of desired test frequencies. The computer control is preferably still further operable to automatically broadcast at least one frequency for each of a plurality of selected succeeding patch interconnections utilized during corresponding succeeding circular maneuvers of the client ship.